Windows 10: lack permissions to my documents

I moved the location of "documents" to a different drive, and that seems to work pretty well for me. so far, no problems.

 

I jumped on the Win10 TP bandwagon at build 10074 and was fine until build 10166, at which point I lost access privileges to /Documents and /Games and possibly other directory locations. Any file edited in Word, for example, has to be saved to OneDrive because all my local files are locked as "read only." Going into Windows Explorer and manually changing permissions fails - everything reverts to "read only" immediately afterward.

I read elsewhere that this kind of problem can happen when a user profile is corrupted, so I followed Microsoft's official instructions for addressing corrupted profiles in Win8.1, hoping it would do the trick in Win10 (I am currently on build 10240 and still have the same inability to save files locally from within apps like Word or games that I am playing). Unfortunately, they require me to copy the contents of My Documents from the corrupted profile to a new profile, but I am entirely unable to open My Documents. Given that Win10 uses My Documents only as a symbolic link, which directories do I really need to copy to test whether the problem is just a corrupt user profile? Many thanks in advance for suggestions (including telling me that this should be opened in a separate thread; I'm often unclear when that is merited, especially when my problem seems highly similar to the OP's problem).